If you are contemplating a trip to the Alps, best go sooner rather than later. The longer you leave it, the less likely you are to find much sign of the glaciers.

They have drawn generations of climbers and tourists to the Alps from Europe and beyond. But since 1850, western Europe's glacial area has shrunk by up to 40%, and the volume by more than 50%.

The melting is happening, and it appears to be gathering pace. Scientists from Zurich University have monitored two specific regions of the Swiss Alps, the Engadin and the Simplon, for approaching half a century.

This year they reported "a pronounced and dramatic shrinkage of both the extent and number of ice bodies".

"In the Engadin", they said, "24 of the investigated 54 ice patches have vanished since 1955. In the Simplon area, 10 of 31 ice bodies have melted away completely since 1967."

Sub-surface melting

Longer-term studies suggest that the Alpine glaciers have been retreating for the last 150 years, and some scientists believe they could disappear completely by 2050.

The melt is on across the Alps

Satellite studies carried out by the US Geological Survey's Glims project (Global Land Ice Measurement from Space) reported evidence in June 2001 of glacier shrinkage in the Pyrenees, between France and Spain.

The number of Spanish glaciers has fallen from 27 in 1980 to 13 today.

It is not only the glaciers themselves that are warming, but the rock and soil beneath the surface as well.

Scientists have discovered that Europe's permafrost, the frozen earth covering mountain areas like the Alps, is melting.

Underground temperatures have risen by nearly a degree in the past decade - three times faster than at any other time in the last century. Buildings and villages will be increasingly at risk.

Further afield, the rate of glacier retreat in Russia's Caucasus mountains is about the same as Switzerland's.

Sign of change

Beyond Europe, the ice fields on the summit of Kilimanjaro in east Africa could melt completely in the next 20 years if the Earth continues to warm at the rate many scientists expect, according to Professor Lonnie Thompson, of Ohio State University, US.

He said comparisons with previous mapping showed 33% of Kilimanjaro's ice had disappeared in the last two decades - 82% had gone since 1912.

Melting permafrost threatens installations

Professor Thompson said Quelccaya in Peru, the only true ice cap in the tropics, had retreated 32 times faster in the last two years (1998-2000) than during the 20 years from 1963 to 1983.

"As a result of recent global warming, many tropical glaciers around the globe may disappear completely by 2020. Apart from the dramatic impact this will have on local communities, it is also a potent sign that the Earth is undergoing enormous changes," he said.

Warmest yet

A global study of 160,000 mountain glaciers and ice caps shows that the volume of the world's glaciers is declining, and that the rate of ice loss is continuing to speed up.

It is the smaller glaciers at low latitudes that seem to be worst affected, though there is evidence of loss in mid-latitudes as well.

The glaciers of the Tien Shan mountains between Russia and China have lost 22% of their ice volume in the last 40 years, while ice cores from eastern Tibet show the last 50 years to have been the warmest yet.

Until recently, though, there seems to have been little change in high-latitude glaciers, especially in the Arctic.